S33-01 : Bacterial chemotaxis as a strategy for survival in soil ecosystem

Kato Junichi¹,Oku Shota¹,Hida Akiko¹,Tunchai Mattana¹,Vangnai Alisa²,Tajima Takahisa¹
1Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, 2Department of Biochemistry, Faculty of Science, Chulalongkorn University
There are two facts: 1) more than 50 genes are required for bacterial motility and chemotaxis, 2) most of environmental bacteria have maintained motility and chemotaxis even though they have evolved under natural selection for very long periods of time. It is a circumstantial evidence that chemotaxis gives chemotactic bacteria advantages in survival in natural environments. It has been vaguely considered that they are advantages in exploring growth substrates and host organisms (for symbiosis, parasitism, infection, etc.). But, is it correct? If so, which chemoattractants are involved in these advantages?  We could not answer these questions because of delay of molecular biological research of chemotaxis, especially functional characterization of chemotaxis sensory proteins in environmental bacteria. Since it is chemotaxis sensors that determine which compounds a certain bacterium chemotactically responds to, their characterization are essential to understand the role of chemotaxis in survival in ecosystem. We have successfully characterized many chemotaxis sensors in environmental bacteria including plant growth promoting bacteria and plant pathogen, and investigated their relationship to plant root colonization and plant infection. In this presentation, I will introduce our recent results about chemotaxis in environmental bacteria and its roles in their ecological behaviors.

keywords:chemotaxis,ecological interaction,bioremediation,Ralstonia solanacearum,Pseudomonas fluorescens